Studies conducted on Arthrobacter species during the past few years indicated that in these bacteria, regulation of sugar transport and inducible enzyme synthesis involved several novel features. It was the overall objective of this research project to elucidate the details of these mechanisms and reactions so that the nature of the regulation could be better understood. It has been found that a. pyridinolis possesses both a phosphoenolpyruvate-dependent phosphotransferase system and a respiration-coupled transport system for both fructose and rhamnose. Moreover, there is a requirement for the latter system to be active (and energy-coupled) in order to allow induction of the inducible components of the phosphotransferase system. The nature of the inducer and factors influencing the induction will be investigated in detail this year. Several aspects of the respiration-coupled transport system will also be studied: (1) the relevant dehydrogenase and mutants lacking this enzyme; and (2) systems for phenylalanine and gluconic acid which are independent of exogenous electron donors (unlike those already characterized).